This is a request for help with a simple difference calculation for two
adjacent cells, as described below.

The example below may well be more understandable than my attempt to explain
what is needed.

Function and argument needed for the positive or negative difference between
the amount for a given days sales last year and the amount for a given days
sales this year.

Last years daily sales are the standard, so if this years daily sales are
more than last years sales, the difference will be a positive amount, but if
this years daily sales are less than last years, the difference will be a
negative amount.

Running sums will be shown for each column.

Below is the proposed layout example. Each row is for one day in a given
month. Amounts shown are for four days only. The SUM totals are at the bottom
of each column.

Last Year This Year Difference
Gross Sales Gross Sales
1214.00 1113.00 -101.00
1065.00 1712.00 647.00
2301.00 2812.00 511.00
4216.00 3330.00 -886.00

SUMs for the month

8796.00 8967.00 171.00

All the function arguments my search has turned up are for more complex
difference function arguments. I am at wits end. Your help will be deeply
appreciated.